Some analysts and experts said a complete dismantling of the country’s nuclear program was unattainable. But lawmakers urged the White House to increase sanctions to ramp up the pressure on Iranian officials.

“Any agreement that does not require the full and complete halting of the Iranian nuclear program is worse than no deal at all,” said House Majority Leader Eric Cantor (R., Va.) in a statement. “Sanctions brought the Iranians to the table, but history tells us to be wary of their tactics. We should not race to accept a bad deal, but should keep the pressure until the Iranians are willing to make significant concessions.”

Both Democratic and Republican lawmakers were concerned about the deal emerging in Geneva, which would have Iran roll back its nuclear enrichment program in exchange for an easing of international sanctions. Negotiators emphasized Friday that important details remained unresolved.

“If Iran intends to show good faith during these talks, it must at a minimum abide by United Nations Security Council resolutions calling for a halt to enrichment, and it is my hope that we achieve much more,” said Rep. Eliot Engel (D., N.Y.) in a statement Friday. “I forcefully reject any notion that Iran has a ‘right’ to enrichment, a view which the administration has publicly articulated on numerous occasions.”

Sen. Ted Cruz (R., Texas) called the deal being pursued “terrible” and said it would endanger the country.

“To lift economic sanctions on Iran in exchange for an amorphous promise to pause their immediate efforts to acquire nuclear weapons makes no sense whatsoever,” he said in a statement released Friday. “It is almost surely unverifiable, and lifting the sanctions will only encourage Iran to surreptitiously continue to develop nuclear weapons–weapons that, if acquired, pose an existential threat to America and our allies.”

Mr. Cruz also urged the administration not to “abandon” Israel, whose prime minister, Benjamin Netanyahu, has rejected the emerging deal and reiterated Friday that Israel would do “everything it needs” to defend itself. In the last months Mr. Netanyahu has publicly urged the U.S. to increase sanctions on Iran.

President Barack Obama has twice urged Congress to hold off on administering tougher sanctions while talks play out. The House passed a bill in July ramping up sanctions, but the Senate has held off on moving its version of the bill along, at the administration’s request.

Sen. Tim Johnson (D., S.D.), chairman of the Senate Banking Committee, reiterated Friday that the committee would not make a decision on pressing ahead with additional sanctions until negotiations are finalized.

Analysts said it is unrealistic for legislators to expect Iran to dismantle its entire nuclear program, and said Friday’s talks represent a key step forward. Some said the deal as outlined would allow talks toward a larger agreement continue with assurances that Iran will not move closer to a weapons capability.

“This is a great opportunity to put time back on the clock,” said Joel Rubin, director of policy and government affairs for Ploughshares Fund, which promotes nuclear disarmament. “It’s also a great opportunity to really test and verify Iran’s intentions … to see if Iran is serious about its stated goal of not building a nuclear weapon.”

Added Alireza Nader, senior international policy analyst at the Rand Corporation, a global policy think tank: “It’s important for people who are opposed to the deal to realize that we don’t have a lot of time. Iran’s nuclear program has advanced …Given the realities on the ground, a good deal is one in which Iran halts or rolls back its activities.”

Fears both in Congress and in the Middle East that Iran and the U.S. are reestablishing a relationship too quickly are unfounded, Mr. Nader added. “I don’t think Iran and the U.S. are going to have great relations any time soon,” he said.

Jamal Abdi, policy director of the National Iranian American Council, said some U.S. legislators are engaging in “fantasies” that the goal of negotiations is to strip Iran of its uranium enrichment capabilities. “If that was the goal from the beginning, then all of these legislators should have just come out and said they wanted war, because that’s not going to happen,” he said.

About Washington Wire

Washington Wire is one of the oldest standing features in American journalism. Since the Wire launched on Sept. 20, 1940, the Journal has offered readers an informal look at the capital. Now online, the Wire provides a succession of glimpses at what’s happening behind hot stories and warnings of what to watch for in the days ahead. The Wire is led by Reid J. Epstein, with contributions from the rest of the bureau. Washington Wire now also includes Think Tank, our home for outside analysis from policy and political thinkers.